An organic bulk heterojunction photodetector
(OPD) is fabricated on the basis of a blend of poly(3-hexyl
thiophene):1-(3-methoxycarbonyl)-propyl-1-1-phenyl-(6,6) C61.
The OPD responsivity is calculated from current density-voltage
characteristic (J-V) under green-LED illumination obtaining
1 A/W. Frequency response at different biases is measured, which
shows a high ¿3-dB cutoff frequency of 343 kHz at ¿3 V.
Impedance measurements are carried out at different reverse
biases, and the results are fitted with a small signal equivalent
circuit. The device cutoff frequency (fc) can be estimated with the
parameters extracted from this circuit obtaining good agreement
between measured and calculated fc.